A wide variety of catalysts are employed at various locations in a refinery. Hydrotreating catalysts allow for removal of contaminants such as sulfur and nitrogen from feedstocks. Dewaxing and hydrocracking catalysts allow for modification of boiling point and/or cold flow properties of feeds. Hydrofinishing catalysts allow for addition of hydrogen to unsaturated functional groups in a feedstock. For many types of catalysts, the state of the fresh catalyst when shipped by the manufacturer does not correspond to the desired state for the catalyst during hydroprocessing. In order to prepare the catalyst for use or “activate” the catalyst, a variety of procedures have been employed.
One of the difficulties in activation of catalysts occurs when multiple types of catalysts are present in a single reactor or reactor train. For example, it may be desirable to have a reactor or reactor train that contains one or more initial beds of a hydrotreatment catalyst followed by one or more beds of a dewaxing catalyst. A typical hydrotreatment catalyst often includes Group VI and Group VIII metals on a refractory support, such as cobalt-molybdenum or nickel-tungsten on alumina. The metals on a hydrotreating catalyst are typically sulfided for use during a hydrotreatment process. By contrast, many dewaxing catalysts include a Group VIII noble metal, such as Pt, Pd, or bimetallic combinations of Pt and Pd, on a support having a higher acidity than an amorphous alumina or other refractory support. Examples of acidic supports include zeolites and supports from the M41S family of supports. The Group VIII noble metals in such dewaxing catalysts are typically poisoned by the presence of sulfur, leading to a lower overall reactivity. As a result, a feed containing a sufficient amount of sulfur to assist with sulfiding the Group VI and Group VIII metals on a hydrotreating catalyst is potentially a feed that will reduce the activity of a Group VIII noble metal dewaxing catalyst.
U.S. Pat. No. 7,220,350 describes methods for selectively activating a dewaxing catalyst using a feed that contains, for example, at least 100 wppm of an oxygenate. The dewaxing catalysts include catalysts having Group VI and Group VIII metals, with Group VIII noble metals being indicated as specific example. As dewaxing catalysts with a wide variety of metals are described, it is noted that the dewaxing catalysts can be either sulfided or unsulfided prior to being exposed to oxygenate. It is noted that the examples describe using a catalyst with Pt supported on a ZSM-48 zeolite in a reduced state, as opposed to a sulfided state.